As everyone gears up for the holiday season, many families find themselves baking Christmas cookies and other desserts to get in the holiday spirit. You probably are not thinking of chemistry when baking a cake, but baking is all about chemical reactions between ingredients. These chemical reactions allow separate ingredients to smoothly mix with each other to produce a delicious dessert.
An essential ingredient to every holiday treat is flour; wheat flour, the most commonly used type of flour, contains high levels of gluten. Gluten is made up of both Gliadin and Glutenin proteins; when these proteins combine with water, they form hydrogen bonds and disulfide bridges with each other and results in the typical “batter” consistency. However, as the batter is kneaded, the glutenin is repeatedly relaxed and exerted, which establishes cohesive gliadins and therefore improves the batter’s elastic consistency.
Additionally, essential agents such as yeast, baking soda, and baking powder further improve the dough’s viscosity by giving it its lightness through chemical reactions. Baking soda chemically reacts with the acids present in the dough to produce carbon dioxide, which is then handled by the Saccharomyces Cerevisiae, otherwise known as baker’s yeast. This single-celled fungus gives the dough a delicate consistency by releasing carbon dioxide bubbles when the batter is cooking in the oven. The yeast organisms release the trapped carbon dioxide by feeding off of sugars and starch present in the dough, and this causes the dough to rise. Sugar can also act as a catalyst for the yeast’s functions. Baking powder also releases carbon dioxide bubbles when the dough reaches a certain temperature in the oven. Watching the dough slowly rise in the oven is one of the best parts about baking, but very few know why it occurs; now you know what is going on inside the batter on a chemical level!
Cookies don’t only rise in the oven; they also transition from a pale color to a rich, golden brown color. This is caused by the sugar; when the surrounding oven temperature reaches 300 degrees Fahrenheit, the Maillard reaction occurs. This is a chemical reaction between amino acids and reducing sugars, where both are broken down and rearranged. The complex process that starts with the reaction between a reducing sugar and amine, which creates glycosylamine. Sometimes, flour can be the source of both the reducing sugar and protein for this process; or it can be magnified by the addition of eggs, which acts as the protein, and sugar, which acts as the reducing sugar. This process results in the baked treat browning in the oven, due to the melanoidins and other organic compounds that are released through the dough’s crust at high temperatures. It can also produce pleasant aromas and enhance flavors, although aromatic strength is directly dependent on the oven temperature.
Caramelization is the final reaction to occur in the oven. As the oven reaches 356 degrees Fahrenheit, the sugar molecules break down and release water in a gaseous form. During the beginning stages of this process, diacetyl is produced. After this, esters, lactones, furan molecules, and maltol are produced. All of these chemicals enhance the flavor of the baked treat to give it a more caramel and toasty taste.
The holiday season is filled with family bonding, having fun with friends, and spending time with loved ones. Baking is a great way to pass the time with the people important to you, and baking can be a little more fun now that you know the chemical reactions that transform tasteless ingredients like flour and baking powder into delicious treats!
Sources:
Medeiros, Vasco. “The Chemistry of Baking.” AZoLifeSciences, 27 January 2022, https://www.azolifesciences.com/article/The-Chemistry-of-Baking.aspx. Accessed 25 December 2022.
Smith, Brett. “Chemical Reactions That Occur During Baking.” Sciencing, https://sciencing.com/chemical-reactions-that-occur-during-baking-12731635.html. Accessed 25 December 2022.
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